Charged particle beam devices have many functions in a variety of industrial fields, including, but not limited to, inspection of semiconductor devices during manufacturing, exposure systems for lithography, detection devices and testing systems. Thus, there is a high demand for structuring and inspecting specimens within the micrometer and nanometer scale.
In particular, the advancement of semiconductor technologies has created a high demand for structuring and probing specimens within the nanometer scale. Micrometer and nanometer scale process control, inspection or structuring is often performed with electron beams. Probing or structuring is often performed with electron beams which are generated and focused in electron beam devices. Examples of electron beam devices are electron microscopes, in particular scanning electron microscopes (SEM), or electron beam pattern generators. Electron beams offer superior spatial resolution compared to photon beams, due to their short wavelengths at comparable particle energy.
For semiconductor manufacturing, throughput can be a significant limitation in tools for scanning a given geometry in its entirety. Assuming a SEM resolution of 1 nm, a 10 mm2 die contains 10E14 pixels. Accordingly, for covering the entire layout, a fast inspection architecture is desired. For achieving high throughput at a desired signal-to-noise ratio (SNR), it is desired to have an electron beam device with a high electron beam intensity.
However, at high electron beam intensity the interaction between electrons of the electron beam have an increasing effect on the beam. Due to the electron-electron interactions, the energy and spatial resolution of the beam is decreased. Therefore, measures to mitigate the electron-electron interactions of the beam have been devised, such as broadening the primary electron beam. However, there still exists a need to further reduce the effects of electron-electron interactions.
A further need is allowing the beam to be tilted so that it impinges on the specimen at an inclined angle. By tilting the beam, additional image information can be obtained, allowing e.g. for a three-dimensional-type imaging of the specimen. Ideally, images at various tilt angles can be combined with each other. This is possible by tilting the beam electronically. However, electronic tilting of the beam produces additional aberrations such as a chromatic aberration of the electron beam, thus reducing the image quality.